Method of obtaining zinc by electrolysis.



Patented May 27, |902.

(Application led Aug. 12, 1901.)

4 Sheets-Sheet l.

(N0 Model.)

i I l i l l l i l l l Tn: Nonms PETERS co, immuun-10wnswwommac No. 70|,2l5. Patented May 27, |902. L. MUND.

METHOD 0F OBTAINING ZINC BY ELEGTROLYSIS.

(Application led Aug. 12, 1901.)

(No Model.) 4 Sheets-Sheet 2.

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No. 70|,2l5. Patented May 27, |902.

L. MUND.

METHOD 0F OBTAINING ZINC BY ELECTROLYSIS.

(Application led Aug. 12, 1901.) 4(No Model.) 4 Sheets-Sheet 3.

we Nowms arias co, Pneovumo. wAsmNmoN. n. c

No. 70|,2I5. Patented May 27, |902.

L. MUND.. METHOD 0F OBTAiNlNG ZINC BY E'LECTROLYSIS.

(Application filed Aug. 12, 1901.)

4 Sheets-Shet 4.

(N0 Model.)

mi Nomus PETERS cn. wmouwo.. WASHINGTON, D. c

UNTTEE STATES `ATENT OEEICE.

LUDVIG MOND, OF LONDON, ENGLAND.

METHOD OF OBTAINING ZINC BY ELECTROLYSIS.

SPECIFICATION forming part of Letters Patent No. 701,215, dated May 27, 1902.

Application filed August 12. 1901. Serial No. 71,775. (No specimens.)

To all whom it may concern.:

Be it known that I, LUDWIG MOND, a citizen of England, residing at 20 Avenue road, Regents Park, London, England, have invented a certain new and useful Improved Method of Obtaining Zinc by Electrolysis, (for which I have applied for a patent in Great Britain, dated March 19, 1901, No. 5,76%) of which the following is a specification.

For depositing zinc from its solutions, and more particularly from alkaline solutions, by electrolysis a great difficulty has been found in obtaining the m etal in a coherent form. It is usually obtained in the form of a spongy mass, which oxidizes so readily on being Withdrawn from the electrolytic bath that on attempting to melt it only a small percentage of the zinc originally deposited is obtained as metal, the bulk presenting itself as oxid. Various means have been proposed to overcome this difficulty, such as depositing the zinc upon revolving cathodesin the form of disks or cylinders,which are partlyimmersed in the electrolyte. Vith great precautions a coherent rnetallic deposit of zinc can be obtained in this way up to a certain thickness, rarely exceeding, however, one-eighth of an inch, after which the deposit becomes spongy. According to my present invention I entirely overcome this difficulty and obtain coherent lnetallic deposits of any thickness by subjecting the metal to a constant rubbing action both longitudinally and transversely under pressure while it is being deposited. For this purpose apparatus of various forms may be ernployed. For instance, I may make the cathodes upon which the zinc is to be deposited cylinders of conducting material and arrange several of them touching one another inone electrolytic bath. These cylinders are provided with shafts moving in bearings, which are mounted so that they can slide,and I apply pressure upon all or several of these cylinders by means of weights, springs, levers, or other mechanical device, which presses the cylinders against each other and at the same time allows them to move farther apart as the thickness of the zinc deposited upon them increases. All the cylinders may be rotated separately by any convenient motor; but I prefer to drive only some of them, the others being rotated byfrictional contact. As stated above, the said apparatus can be constructed in variously-modified ways for carrying out my invention. By way of example I will describe some of these with reference to the accompanying drawings.

Figure 1 is a part longitudinal section of one construction of the apparatus with the cathode-cylinders arranged in a horizontal ro'w. Fig. 2 is a part plan. Figs. 3 and 4 are respectively an enlarged cross-section and a front view of one of the bearings of the shaft of cylinder ct. Fig. 5 shows a longitudinal section of another construction, in which the cathode-cylinders have their axes vertical. Fig. 6 showsa cross-section of the same. Fig. 7 shows a vertical section of the construction in which horizontal cathode-cylinders are superposed; Fig. 8, a section on line 8 8; Fig. 9, a sectional plan, and Eig. 10 an enlarged detail, of this construction.

Referring to Figs. 1 and 2, the cylinders a and b b have their shafts mounted in bearings e and d d, pressed against each other by springs c or their equivalents. inders may be rotated'by any convenient motor; but I prefer to drive only one of them, b, as by a belt fon pulley g, as shown, the others, ce b', being rotated by frictional contact. I make these cylinders of slightly-dierent diameters, a smaller between each two larger, so that the same points on their circumferences do not come in contact until after many revolutions. I also give alternate cylinders Ct, besides rotation, a to-and-fro longitudinal motion for producing the above-described rubbing action and also to avoid the formation of grooves in the deposited metal. This to-and-fro motion, which need not exceed an inch, may be obtained, as shown, by cutting a cam-groove in one of the bearings and mounting on the shaft, which works in it a roller k, fitting loosely in this groove. The bearings of the cylinder-shafts are insulated and connected to the negative terminalv of a source of electricity, or, as shown in Fig.A 2, each of the cylinder-shafts has on `its end a metallic disk Z, dipping into mercury in an insulated cup m, all of which cups are connected to the negative pole of the source of electricity. The other pole is connected to the amalgam p, which occupies the lower part of the cell. This amalgam is obtained in the known mand All the cyl-- IOO -ferred to.

ner by the electrolysis of sodium or potassium chlorid with a mercury cathode, and when it is employed as anode it should be kept constantly flowing over the bottom of the cell. When such amalgam is not available, anodes may be employed of carbon or of platinum, iron, or other metals that are not oxidized by electrolytic oxygen in alkaline solution.l

In order to facilitate the removal of the deposited zinc, the cylinders should be coated with alittle graphite or paraiiin or any other suitable substance which prevents contact of the deposited zinc with the metal of the cylinder.

In the construction shown in Figs. 5 and 6 the cathode-cylinders a b are arranged with their axes vertical, the middle one, ct, receiving a slight longitudinal up-and-down motion by means of a cam-groove in its lower bearing c, as in the first-described construction. It is also of a somewhat-smaller diameter than the cylinders b b for the Iabove-described purpose. The lower bearings c cl d are carried loose in a trough-shaped guide n, at the ends of which are provided the springs e for pressing the cylinders b against a. A similar arrangement is also provided for the upper bearings c d d', the supporting-guide n' being in the form of two bars. The cathodecylinders a b b are in this case hollow, and the cylindrical part of each is insulated from the two ends by rings o of insulating material, such as ebonite, the cylindrical part being connected to the electric circuit by contact-spring brush m, under which the cylindrical surface slides. y

The anodes consist of metal plates p, extending the Whole length of the cell and corrugated, as shown in Fig. 8, hereinafter re- The one cylinder b is driven by a belt-pulley q and imparts motion to the others by frictional contact.

In the modication shown in Figs. 7 and 8 the cylindrical cathodes a b b have their axes horizontal and are superposed. In this case the cylinders are pressed against each other by Weights 7' r, which are mounted on the reference to Figs. 5 and 6, and the corresponding parts are marked with the same reference-letters, and need, therefore, no further description. pp are the anode-plates, which are preferably corrugated, as shown in Fig. 8, so as to have all their parts approximately equidistant from the surfaces of the cylinders. The cylinders a b b are connected to the circuit by a contact-spring brush m, applied to the top roller. The cathode-cylinders being hollow in this case, as also in the arrangement shown in Figs. 5 and 6, a suitable packing has to be provided to prevent the electrolyte from penetrating into them at the center. This may conveniently be effected, as shown at Fig. lO, where a caoutchouc or ebonite ring s is compressed in the recess of the boss, so as to form a water-tight joint by means of a steel washer t and screwnut u.

Having thus described the nature of thisin- Vention and the best means I know of carrying the same into practical effect, I claim- A method of obtaining zinc in a solid metallic condition which consists in depositing the zinc on separate cathodes by electrolysis and simultaneously therewith subjecting the deposited zinc upon one cathode to a longitudinal and transverse rubbing action of the zinc deposited upon the other cathode under pressure.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

LUDWIG MOND.

lVitnesses:

ARTEIUR N. CoLLosoN, GEORGE READY. 

